A. Field of the Invention
The present invention relates to blood vessel graft systems for repairing aneurysms, and more particularly to a catheter-based graft system for repairing aortic aneurysms by deploying a graft within a blood vessel via percutaneous entry into a femoral artery of a patient.
B. Description of the Prior Art
An aortic aneurysm is a very common deteriorating disease typically manifested by weakening and expansion of the aorta vessel wall at a region between the aorto-renal junction and the aorto-iliac junction. Aneurysms affect the ability of the vessel lumen to conduct fluids, and may at times be life threatening, for instance when rupture of the vessel wall occurs. A standard treatment for repairing an aneurysm is to surgically remove part or all of the aneurysm and implant a replacement prosthetic section into the vessel, however such surgery is generally postponed until the aneurysm has grown to a diameter greater than five centimeters. With aneurysms over five centimeters in diameter, the risk of complications is greater than the risks inherent in surgical excision and grafting of the aneurysm. Consequently, aortic aneurysms measuring greater than five centimeters in diameter, and those showing a rapid increase in size, are generally surgically removed and grafted as a matter of course, before rupture occurs.
The standard procedure for repairing an aortic aneurysm requires one or two days of preparing the large and small intestines prior to hospitalization. The operation itself generally takes one to three hours to perform, and necessitates several units of blood for transfusion. The patient commonly remains hospitalized for several days following surgery, and requires as much as three months recuperation time before returning to work. Moreover, there remain significantly high rates of mortality and morbidity associated with the standard procedure. The mortality rate is as high as eight percent, while the morbidity rate includes incident complications such as blood loss, respiratory tract infections, wound infections, graft infections, renal failure, and ischemia of the bleeding intestine. The mortality and morbidity rates for this type of major surgery are also often influenced by the fact that the typical aortic aneurysm patient is elderly and therefore less able to withstand major surgery, including anesthesia.
Other treatments for repairing an aneurysm involve deploying a graft device at the aneurysm site via a catheter traveling through a femoral artery. Conventional tubular aortic replacement sections, however, are generally considerably larger in diameter than the femoral artery and therefore cannot be inserted through the femoral artery lumen to the site of the aneurysm. Expandable graft devices suitable for catheter delivery and deployment have been proposed, as in U.S. Pat. Nos. 4,140,126 and 4,562,596 by Choudhury and Kornberg, respectively, however the expanding structures of the devices are cumbersome and difficult to operate.
U.S. Pat. No. 5,104,399 to Lazarus discloses an artificial graft device having staples at proximal and distal ends thereof for fixing the graft within the vessel, and a catheter-based deployment system including a tubular capsule from which the graft is deployed. The graft is of a preselected cross section and length, and is capable of being substantially deformed so as to accommodate to the interior surface of the blood vessel.
The majority of other graft systems, as exemplified by U.S. Pat. No. 5,304,220 to Maginot and 5,151,105 to KwanGett, require additional suturing or other methods for securing a graft. Furthermore, once a graft has been placed inside the lumen, adjustment usually requires a major surgical procedure.
Furthermore, the prior art stainless steel or elgialloy stent grafts carry high leakage rates. Moreover, high incidence of fractures have been associated with stainless steel stent grafts.
An additional problem with grafts in the public domain is the graft in-folding which causes leakage, migration, and thrombosis. Too, those grafts in the public domain such as U.S. Pat. No. 5,507,771 can provide adequate seals only with straight surfaces due to the spring shape and sealing force.
In cases where the aneurysm involves the ipsilateral and contralateral iliac vessels extending from the aorta, it is known to provide a generally Y-shaped bifurcated graft having a primary limb joining with an ipsilateral limb and a contralateral limb. An example of such a graft, and means for surgically implanting same, are described in U.S. Pat. No. 5,387,235 to Chuter. The surgical procedure taught by Chuter involves either surgical isolation of the femoral vessels in the groin to provide direct access to the vessels, or percutaneous entry through both ipsilateral and contralateral femoral arteries.
The difficulties involved with traditional surgical procedures and additional complexities associated with securing grafts make the treatment of aneurysms a very expensive and lengthy procedure. Thus, there exists a need for a treatment for aneurysms which requires minimal preparation and outpatient care, and which provides a safe and percutaneous method for deploying a graft capable of remaining in place without additional suturing or stapling for security.